IF Steven Spielberg is looking for a sequel to Schindler's List, he could do worse than start with this book. Among others, we find here one of the most surprising tales of the Second World War, a unique struggle to save the innocent from Nazi oppression. It is set in occupied Poland around the village of Rozvadow, where hundreds of civilians were saved from slave labour and death by the actions of one agent. Step forward the bacterium Proteus 0X19.

It is, Dr Dixon records, 'an otherwise unimpressive and unimportant bacterium'. But it allowed two Polish doctors, Eugeniusz Lazowski and Stanislav Matulewicz, to fool the German authorities into believing that an epidemic of typhus was raging in their district.

The Germans were petrified that their invasion might bring typhus back into the Fatherland where the disease had not been seen for a quarter of a century. So great was their fear of contracting the disease, that they didn't investigate the Rozvadow incident too closely, and left the people in the area free to live their lives without further intimidation.

The German fears were in one way well-founded. Typhus had been a familiar presence on European battlefields since 1490, when Spanish troops who had been fighting in Cyprus brought it back to Spain, carried by the lice that infested them. The disease killed between two and three million people during the First World War. As Dr Dixon notes in another excellent vignette in this book, it was typhus and 'not the ingenuity of any of his military opponents (which) broke Napoleon's power in Europe' by killing more troops than any of his battles.

The human body fights infection by raising antibodies against the invading organism. In the case of typhus, this is Rickettsia prowazekii; but, oddly, antibodies to the relatively harmless Proteus 0X19 also appear, so that the presence of Proteus antibodies forms a diagnostic test for typhus. Thus the Polish doctors fooled the Germans into believing there was a typhus epidemic in Rozvadow by infecting some of their patients with Proteus.

In the event, Proteus by itself was not quite enough. The Germans were suspicious enough to send a medical investigation team. As Dr Dixon notes, the elderly doctor in charge was cordially received and plied with vodka. That finally did the trick and the local people were left in relative peace.

The saga of Proteus 0X19 is only one of the immensely entertaining anecdotes in this collection of stories about how microbes have shaped the world we live in. Microbes made our physical world: they are, for example, responsible for the oil deposits which we are now burning away. But they have also shaped politics and society. If it was Rickettsia prowazekii that defeated Napoleon, then it was Phytophthora infestans which forced the Fitzgeralds and Kennedys to migrate to America, starting the chain of events that ultimately put John Fitzgerald Kennedy into the White House.

I suppose I should declare an interest, since a few of these tales have appeared (in much shorter form) in the Microbe of the Month column on this newspaper's science page, which I edit. But, in general, I do not like collections of essays: I prefer books that have a connected narrative which moves seamlessly through from beginning to end. This book has forced me to suspend my prejudice.

The book's format may appear old-fashioned and didactic, but it works wonderfully well. One key to its success is simply that each individual narrative is so well written. But there is a deeper point: the author has stepped outside the laboratory to engage with the real world. We humans may think of ourselves as the lords of creation, but Dr Dixon shows that the microbes render our tenure insecure. Power Unseen is ostensibly a book about microbes. The reason it is so appealing is that, in reality, it is about ourselves.